Size controlling apparatus



Sept. 12, 1950 T. A. JAGEN SIZE-CONTROLLING APPARATUS Filed June 25,1946 G MM A m MA MW E Z Patented Sept. 12, 1950 SIZE CONTROLLINGAPPARATUS Theodore A. Jagen', Harrison, N. J., assignor to GeneralMotors Corporation, Detroit, Mich, a corporation of Delaware ApplicationJune 25, 1946, Serial No. 679,128

11 Claims.

This invention relates to size controlling apparatus and particularly togauging apparatus arranged to measure the size of an article and tocontrol a machining operation such as a grinding operation on thearticle.

An object of the invention is to provide an improved and simple gaugingapparatus which controls the grinding of a work piece.

Another object is provide an improved sizecontrolling apparatus whereinelectrical mechanism, responsive to a gauge which visually indicates thesize of a work piece durin grinding, operates to terminate the grindingoperation when the gauge indicates a predetermined work-size.

Another object is to provide an electronic grinding feed control whichis responsive to a gauge that measures the change in size of a workpiece during a grinding operation.

To these ends and also to improve generally upon devices of thecharacter indicated, the invention consists in the various mattershereinafter described and claimed. In its broader aspects, the inventionis not necessarily limited to the specific constructions selected forillustrative purposes in the accompanying drawings wherein:

Figure 1 is a fragmentary end view of a grinding machine including adiagrammatic showing of the electrical circuits and illustrating theoperation of the invention;

Figure 2 is a front elevation of the work gauging mechanism;

Figure 3 is an enlarged fragmentary sectional view taken substantiallyalong the line 33 of Figure 2;

Figure 4 is a fragmentary view of one type of dial gauge used in thisinvention;

Figure 4a shows one form of a pointer contactor mounted in position;

Figure 5 is a front elevation of a dial gauge provided with another formof a pointer contactor; and

Figure 6 is a cross section taken substantially along the line 6-6 ofFigure 5.

Generally considered, a machine tool such as a grinding machine has itstool feeding orgrinding wheel feeding mechanism responsive to a worksizing apparatus that includes a calipertype gauge l0 provided with adial gauge, as H, whose movable pointer [2 indicates with respect to asuitable index or dial graduations the extent of change in size of awork piece W being ground. When this work piece is ground to the desiredpredetermined size, the pointer l2 engages a contaotor, as it, causinelectronic control mechanism to control the feeding mechanism andterminate the grinding operation.

In the illustrated embodiment, the size controlling apparatus is appliedto a grinding machine having a base I5 upon which is slidably mounted awork table 16 arranged to support the work piece W for rotation andaxial reciprocation, and a rotatable grinding wheel I! is fedtransversely towards and from the work piece by a wheel slide 58slidably mounted on the base. The power operated mechanism for feedingthe grinding wheel towards and from the grinding zone may comprise acylinder 2% fastened to the base l5 and containing an axially slidablepiston 22 which is operatively connected to the wheel slide [8 through apiston rod 23 that is slidable through a cylinder head. The direction ofwheel feedin movement is controlled by a reversing valve 25 having threespaced pistons 26, 27 and 28 slidable in a cylinder 30 under control ofan axially shiftable piston rod 32 that slidably extends through an endof the reversing valve.

When the reversing valve pistons are in their illustrated full linepositions, fluid under pressure from a pipe 33 enters the cylinder 30between the pistons 21, '28 and flows out through a pipe 34 into therearward end of the cylinder 20 causing a forward movement of the piston22' which results in a feeding of the grinding wheel towards'and intothe work piece W. Fluid from the forward end of the cylinder 20 nowexhausts through a pipe 35 into the cylinder 36 between the pistons 26,2! and out through an exhaust pipe 36 and through a throttle valve 37which is adjusted to control the rate of grinding wheel feed. When thereversing valve pistons are shifted to their dot-dash indicatedpositions as by a manual shift member 38, or by a solenoid 46' to belater described, fluid under pressure from the pipe 33 flows between thepiston 25, 21 and through the pipe 35 into the forward end of thecylinder 20 causing arearward movement of the piston 22 with aconsequent withdrawal of the grinding wheel away from the work piece W.This Withdrawal of the grinding wheel will be much more rapid than thegrinding wheel infeed since the fluid from the rearward end of thecylinder 2t now will exhaustfreely through the pipe 34, between thepistons 21, 28 and out through an exhaust pipe 42.

The caliper gauge Hi, which may be of the Arnold type, has a main framet3 that slidably receives a generallyvertical gauge plunger 44 wheel, atthe other end pivotally supports a bracket 50 which grips a dovetailedrearward portion of the upper end of the main frame 43. A housing 52,fastened to the wheel slide 18, pivotally supports the lower end of thearm 48, and

spring mechanism within this housing is regu-- lated to swing the arm 48upwardly with sufiicient pressure to overcome the weight of the gaugeassembly [0 and maintain the hardened contact on the finger in lightengagement against the underside of the work piece W during gauging. Thegauge assembly H1 is located sufficiently forwardly of the pivotalmounting for the bracket 50 to cause the gauge to swing towards the workpiece and maintain the hardened contact of the finger 45 in lightengagement with the work piece during gauging.

The dial gauge H has a casing 53 from which projects an axially slidablestem 54 urged outwardly from the casing as by a spring 55, and connectedthrough amplifying mechanism, as a rack portion 55 and gears 51, 58 and59, to position the pointer l2 with respect to a graduated gauge dial.The upper end of the plunger 44 has a head 82 (Fig. 3) slidably mountedin the main frame 43 and urged downwardly by a spring pressed arm 63whose downward movement is limited by a stop screw 64 to prevent injuryto the dial gauge. A dovetailed projection 55 on the underside of thedial gauge and parallel to 1 the gauge stem 54 slidably fits within Wayson a laterally extending main frame projection 66 to angularly supportthe dial gauge conveniently to the machine operator. The movable gaugestem 54 extends through an aperture in the main frame and has a roundedend which engages an overlying reentrant face 61 on the head 52. Avertical movement of the plunger 44, in response to a change in size ofthe work piece during grinding, causes a movement of the face 61resulting in a movement of the gauge stem 54- and a consequentmeasurement of change in work size by the pointer on the graduated gaugedial. A plate 58 having an upwardly projecting lug fitting within arecess in the gauge casing has at each end a slot through which extendsa screw Hi threaded into the frame projection 65. A stud 'll journalledin this frame projection 66 and having an eccentric head may be turnedto longitudinally shift the plate 68 and axially position the gauge stem54 for initially adjusting the gauge pointer position with respect tothey movable plunger 44 after which the screws 10 may be tightened tomaintain this adjustment.

A crystal (3 of plastic or other suitable transparent insulatingmaterial, throughwhich the pointer position may be observed, is grippedby a bezel l4 threaded or otherwise rotatably mounted on the casing 53.The contactor 13, which may be of suitable electro-conductive metal asbrass, is shown as a stud projecting inwardly from the crystalsufiiciently to be engaged by the pointer i2, this stud being held inposition by a screw 75 passing through a hole in the crystal. The dialgauge is preferably of the 4 shockproof type as shown in Figure 4wherein-inward movement of the stem 54 causing a clockwise pointermovement, as viewed in Figure 2, will not be injurious to the gaugeafter the pointer stops against the contactor l3. As illustrated, thecoaxial gears 51 and 58 are not positively connected and an arm 16secured to the gear 58 is engageable with an arm 11 secured to the gear51. A helical spring tends to rotate the gear 58 to position the arm 16against the arm 11. When the clockwise pointer movement, as viewed inFigure 2, is stopped by the contactor IS, the gear 58 and the arm 16remain stationary while further inward movement of the stem 54 onlycauses the arm "H to retreat from the arm 16.

In the event that the dial gauge does not embody the"shockproofmechanism of Figure 4, I employ a hairspring contactor arrangement asshown in Figures 5 and 6 which permits the pointer 12 to swing pastcontact-making position without causing damage to .the dial gauge. Ahelical hairspring I8 of suitable elec tro-conductive metal is axiallysecured between the crystal l3 andthe pointer l2 by a stud 8U fastenedthrough the crystal. A generally radially extending hairspring arm 82 isurged counterclockwise by the hairspring against a stop 83 that may besimilar to the contactor I 3 but which does not project into a pointerengaging position. An inwardly projecting hairspring end 84 isintercepted by and makes electrical connection with the pointer when thepointer swings to a position beneath the stop 83. Due to the resiliencyof this light hairspring, the pointer may swing past this stop 83, whilecontacting the hairspring.

A stop 85, which also may be similar in construction to the contactori3, is fastened through the crystal 13 to the right of the contactor H3or to the right of the hairspring end 84, to prevent the pointer l2 fromswinging counterclockwise into a circuit making position. The bezel 14is rotatably adjusted to locate this circuit making position of thepointer 12 and is fastened in this adjusted position by a clamping screw86.

The mechanism of a dial gauge is delicate, and the pointer as well asother small parts would be ruined by any strong flow of electricitytherethrough. Hence, I employ an electronic control device wherein theextremely minute current flow in the grid circuit of an electronicvacuum valve passes through the pointer 12 and the contactor I3 or thehairspring 18. One satisfactory electronic control circuit which hasbeen found successful, includes an electron tube such as a three elementvacuum valve 81, having a filament or cathode F heated by a battery A; agrid G and a plate P. The coil of a normally open-circuit relay 88 isconnected in series between the plate P and the positive terminal'of abattery B; The contactor l3 or the hairspringstud Bll'is connected by awire 90 to the grid G and'to one end of a-current limiting resistorRwhose other end is connected to the negativeterminal of a grid.

bias battery C whose positive terminal is connected to the negativeterminals of batteries A and B. To complete the grid circuit to thepoint-, er, the pointer is grounded through the casing 53 and a groundwire 91 is connected to the negativeterminal of the battery A.

vIn operation, while the caliper type gauge I 0 is located on theavorkpiece during grinding and;

prior to circuit making position of the pointer 12, the grid biasbattery C maintains the grid G negative andn'o current flows in theplate circuit through the relay 88 which is normally in open circuit.When the work piece is reduced to desired predetermined size, thepointer l2 engages the contactor 13 or the hairspring end 8d therebycausing the grid G to be at cathode potential. This results in currentflow in the plate circuit and: energizes the relay 88 which closes apower circuit through wires 92 and 93 causing the solenoid 40 to becomeenergized and act through an armature fi l-to shift the reversing valvepistons to their dot-dash indicated reverse positions. This electroniccontrol is extremely sensitive and rapid acting causing the grindingwheel to immediately withdraw from grinding position when the pointer l2reaches circuit closing position which corresponds withthe pointermeasurement of desired work size. When the caliper gauge assembly isremoved from the work piece W, the pointer 12 swings counterclockwise toa stop position against the stop 85 and the grid G again becomesnegative causing a cessation of current flow in the plate circuit anddeenergizing the re lay 88 which breaks circuit to the solenoid Thesucceeding grinding feed is started by operating the manual controlmember 353 to shift the reverse valve pistons back to their full lineindicatedpositi-ons.

I claim:

1. In a work sizing apparatus for controlling the feeding of a grindinwheel into a work piece to reduce the size of the work piece, gaugingmechanism including a movable contact member engageable with the workpiece during grinding, a dial gauge having a pointer in said mechanismmovable over a graduated scale in response to the movable contact memberto measure the size of the work piece, a contactor arranged to beengaged by the pointer for closing a circuit when said pointer reaches apredetermined position of its movement, and electronic feeding controlmechanism including an electron tube responsive 'to the closing of saidcircuit to control a stop of said grinding wheel feed.

2. In a work sizing apparatus, a dial gauge having a pointer movableover a graduated scale on a dial for measuring the size of a work piece,a contactor mounted on said gauge independently of said dial and in aposition to be engaged by the pointer when the pointer is moved in onedirection to a predetermined position, a member preventing the pointerfrom moving in an opposite direction into engagement with saidcontactor, means to simultaneously adjust said contactor and said memberto predetermined positions with respect to said graduated scale, andelectrical connections to the pointer and to the contactor wherebymovement of the pointer into and out of contactor engagement may controlan electrical circuit.

3. In a work sizing apparatus, a dial gauge having a pointer movableover a graduated scale on a dial for measuring the size of a Work piece,a transparent crystal mounted on the gauge for rotatable adjustmentadjacent to said dial, means to secure the crystal in rotatably adjustedposi tion, a contactor secured to the crystal and having a portionarranged to be engaged by the pointer when the pointer is moved in onedirection to a predetermined but adjustable position with respect to thescale graduations, electrical connections to the pointer and to thecontactor whereby the movement of the pointer into and out of contactorengagement may control an electrical circuit, and means stopping thereversed 6 rotation of said pointer at a predetermined dis-' tance fromsaid contactor irrespectiveof the adjusted position of said contactor.

4. In a work sizing apparatus, a dial gauge having a pointer movableover a graduated scale on a dial for measuring the size of a work piece,a transparent crystal adjacent to said dial, a contactor mounted on thecrystal in insulated relation to said pointer and in a position to beengaged by the pointer when the pointer is moved in one direction to apredetermined indicating position on the dial, a stop member mounted onthe crystal and preventing the pointer from moving in an oppositedirection into contactor engagement, electrical connectionsto saidcontactor and to said pointer whereby pointer movement into and. out ofcontactor engagement will control an electrical circuit, means torotatably adjust the crystal for simultaneously positioning thecontactor and the stop member at predetermined positions relative tosaid dia1 graduations, and means to secure said crystal in adjustedposition. i

5. In a work sizing apparatus, a dial gauge having a pointer movableover a graduated scale for measuring the size of a work piece, a stopmember adjacent to but out of the path of pointer movement, a hairspringmounted in insulating relation to the pointer and 'resilientlyurged intoengagement with the stop member, a projection on the hairspring arrangedto be engaged by the pointer for closing an electrical circuit, and saidhairspring being yieldably movable by the pointer away from the stopmember while maintaining electrical contact with the pointer;

6. In a work sizing apparatus, a dial gauge having a pointer movableover a graduated scale for measuring the size of a work piece, a stopmember adjacent to but out of the path of pointer movement, ah'airspring mounted in insulating relation to the pointer andresiliently urged into stop member engagement, means to adjustablyposition the stop member with respect to the graduations of said scale,a projection on the hairspring arranged to be engaged by the pointer forclosing an electrical circuit at a predetermined pointer position, andsaid hairspring being yieldably movable by the pointer away from thestop member while maintaining electrical contact with the pointer.

'7. Ina work sizing apparatus, a dial gauge having a pointer movableover a graduated scale for measuring the size of a work piece, a stopmember adjacent to but out of the path of pointer movement, a hairspringmounted in insulatin relation to the pointer and resiliently urged intostop member engagement, means to adjustably position the stop memberwith respect to the graduations of said scale, a projection on thehairspring arranged to be engaged by the pointer for closing anelectrical circuit when the pointer moves in a measuring direction to apredetermined position, said hairspring being yieldably movable by thepointer away from said stop memprovided with a cathode and'a grid and aplate, means connecting the pointer and the contactor in circuit withsaid cathode and said grid to effect a change in grid bias voltage whenthe pointor engages said contactor, there being a change in current flowthrough the plate in response to a change in grid bias voltage, andmechanism responsive to a change in current flow through said plate.

9. In a Work sizing apparatus, a dial gauge having a pointer movableover a graduated scale on a dial for measuring the size of a work piecewhile the work piece is being ground, a contactor insulated from thepointer and mounted on the gauge in the path of pointer movement, meansto adjust said contactor to a predetermined position to be engaged bysaid pointer, an electron tube provided with a cathode and a grid and aplate, means connectin the pointer and the contactor in circuit withsaid cathode and grid to effect a change in grid bias voltage when thepointer engages said contactor, means providing a current flow throughsaid plate under control of the amount of grid bias voltage, and

mechanism responsive to the current flowthrough said plate forcontrolling the extent of a grinding operation on the work piece.

10. In a work sizing apparatus, a dialgauge having a pointer movableover a graduated scale on a dial for measuring the size of a Work piecewhile the work piece is being ground, a contactor on the gauge in thepath of the pointer movement and insulated from said pointer, means toadjust the contactor to a predetermined pointerengaging position, anelectron tube provided with a cathode and a grid and a plate, meansconnecting the pointer and the contactor in circuit with the cathode andgrid to efiect a change in grid bias voltage when the pointer engagessaid contactor, the amount of current fiow through said plate beingcontrolled by said grid bias voltage, and means responsive to apredetermined amount of current flow through said plate for effecting atermination of a grinding operation on the work piece. 1 11. Ina worksizing apparatus, a. dial gauge having a pointer movable over agraduated scale on a dial for measuring the size of a work piece whileit is being ground, a transparent crystal adjacent to said pointer, acontactor mounted on the crystal and arranged to be engaged by saidpointer, means to rotatably adjust said crystal for locating thecontactor at a predetermined pointer-engaging position, an electroniccircuit including an electron tube provided with a grid and a plate,means electrically connecting said pointer and said contactor in circuitwith the grid to efiect a change in grid bias voltage when the pointerengages said contactor, means providing a current flow through the plateunder control of said grid bias voltage, and grinding controllingmechanism responsive to a change in current flow through the plate ofsaid tube.

THEODORE A. JAGEN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

